Multi-layer sheet structure

ABSTRACT

A multi-layer sheet structure includes, in an exemplary embodiment, a barrier layer having a first side and a second side, at least one thermoplastic layer on the first side of the barrier layer, and at least one thermoplastic layer on the second side of the barrier layer. A cup shaped container may be molded from the multi-layer sheet structure.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority to Provisional Patent Application No. 61/466,326 filed Mar. 22, 2011, which is hereby incorporated by reference in its entirety.

BACKGROUND OF THE INVENTION

The field of the invention relates generally to multi-layer sheet structures and more particularly, to thermoplastic multi-layer sheet structures that are moldable, include at least one layer of a polypropylene, and which is produced with sustainable and renewable ingredients.

Thermoplastic sheets are used in forming various articles, for example, plastic cups and plastic cup shaped containers. Typically, thermoplastic sheets are made from polystyrene resins which may used to form plastic cups and plastic cup shaped containers. Plastic cup shaped containers are sometimes used in single serve coffee maker. Such single, or individual, serve coffee makers typically utilize a single serve fresh ground coffee cup shaped container and the brewed coffee is dispensed directly into a coffee cup. The fresh ground coffee container typically facilitates sealing the coffee grounds in the container until use, so that the coffee grounds are fresh, and typically are sealed at the top with a moisture barrier seal. The cup shaped containers have various sizes which hold only enough coffee to brew one cup of coffee up to a full pot of coffee.

As explained above, single serve coffee containers are configured to be used once and then discarded. Polystyrene plastic, however, is not as environmentally friendly and has a high carbon foot print, as compared to other types of plastics.

BRIEF DESCRIPTION OF THE INVENTION

In one aspect, a multi-layer sheet structure is provided. The multi-layer sheet structure includes a barrier layer having a first side and a second side, at least one thermoplastic layer on the first side of the barrier layer, and at least one thermoplastic layer on the second side of the barrier layer.

In another aspect, a multi-layer sheet structure is provided that includes a barrier layer having a first side and a second side, a first adhesive layer on the first side of the barrier layer, and a second adhesive layer on the second side of the barrier layer. The multi-layer sheet structure also includes a first layer that includes a first polypropylene composition on the first adhesive layer, and a second layer that includes a second polypropylene composition on the second adhesive layer.

In still another aspect, a method of making a multi-layer sheet structure is provided. The method includes connecting a plurality of extruders to a die configured to extrude a plurality of layers, feeding a plurality of thermoplastic materials to the plurality of extruders, and co-extruding a plurality of layers from the plurality of thermoplastic materials to form the multi-layer sheet structure. The plurality of layers include a barrier layer having a first side and a second side, at least one thermoplastic layer on the first side of the barrier layer, and at least one thermoplastic layer on the second side of the barrier layer.

In still another aspect, a multi-layer sheet structure is provided. The multi-layer sheet comprising a first layer and a second layer. The first layer comprise a first polypropylene composition and the second layer comprise a second polypropylene composition.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross sectional schematic illustration of an example embodiment of a multi-layer sheet structure.

FIG. 2 is a cross sectional schematic illustration of another embodiment of a multi-layer sheet structure.

FIG. 3 is a cross sectional schematic illustration of another embodiment of a multi-layer sheet structure.

FIG. 4 is a cross sectional schematic illustration of another embodiment of a multi-layer sheet structure.

FIG. 5 is a schematic illustration of an example embodiment of a forming insert.

FIG. 6 is a perspective view of an example embodiment of a forming base that may be used with the forming insert shown in FIG. 5.

FIG. 7 is a schematic illustration of another example embodiment of a forming insert.

FIG. 8 is a perspective view of an example embodiment of a forming base that may be used with the forming insert shown in FIG. 7.

FIG. 9 is a schematic illustration of another example embodiment of a forming insert.

FIG. 10 is a perspective view of an example embodiment of a forming base that may be used with the forming insert shown in FIG. 9.

FIG. 11 is a schematic illustration of another example embodiment of a forming insert.

FIG. 12 is a perspective view of an example embodiment of a forming base that may be used with the forming insert shown in FIG. 11.

FIG. 13 is a perspective view of an example embodiment of a mold plug.

FIG. 14 is a perspective view of another example embodiment of a mold plug.

FIG. 15 is a perspective view of another example embodiment of a mold plug.

FIG. 16 is a side view of a cup formed from the forming insert shown in FIG. 5 and the forming base shown in FIG. 6.

FIG. 17 is a perspective view of the cup shown in FIG. 16.

FIG. 18 is a side view of a cup formed from the forming insert shown in FIG. 7 and the forming base shown in FIG. 8.

FIG. 19 is a perspective view of the cup shown in FIG. 18.

FIG. 20 is a side view of a cup formed from the forming insert shown in FIG. 9 and the forming base shown in FIG. 10.

FIG. 21 is a perspective view of the cup shown in FIG. 20.

FIG. 22 is a side view of a cup formed from the forming insert shown in FIG. 11 and the forming base shown in FIG. 12.

FIG. 23 is a perspective view of the cup shown in FIG. 22.

DETAILED DESCRIPTION OF THE INVENTION

A multi-layer thermoplastic sheet structure and a method of making the multi-layer thermoplastic sheet structure is described below in detail. The multi-layer sheet structure, in an exemplary embodiment, includes seven layers. Specifically, the sheet structure includes an outer top layer of polypropylene, an inner top layer of polypropylene, a first adhesive layer (tie layer), a barrier layer, a second adhesive layer (tie layer), an inner bottom layer of polypropylene, and an outer bottom layer of polypropylene. Although the sheet structure is specifically described herein as having seven layers, it is contemplated additional layers or fewer layers could be utilized in the sheet. For example, in another embodiment, the sheet structure may include five layers. Specifically, the sheet structure includes a top layer of polypropylene, an adhesive layer (tie layer), a barrier layer, another adhesive layer (tie layer) and a bottom layer of polypropylene. In other embodiments, the multi-layer sheet structure may include from two layers to eight layers. Some examples of a multi-layer sheet structure include a two layer structure that may include two polypropylene layers; a six layer structure that may include a barrier layer, two adhesive layers one on each side the barrier layer, one polypropylene layer on one adhesive layer and two polypropylene layers on the other adhesive layer; and an eight layer structure that may include a barrier layer, two adhesive layers one on each side the barrier layer, three polypropylene layers on one adhesive layer and two polypropylene layers on the other adhesive layer.

The multi-layer sheet structure may be used for forming various articles, for example, cups and cup shaped containers. The multi-layer sheet structure can be molded into various articles using methods known in the art including, for example, pressure forming, thermoforming, plug assisted thermoforming, thermal stamping, vacuum forming, compression forming, and the like. All the ingredients in the multi-layer sheet structure are FDA approved which permit the use of cups and cup shaped containers formed from the multi-layer sheet structure to come in contact with food and liquids for human consumption.

Cup shaped containers may be formed using a plug assisted thermoforming process that utilizes cup shaped molds and plugs to assist the sheet structure into the mold and distribute the materials of multi-layer sheet structure around the mold to form a cup shaped container having a uniform wall, and uniform heel and the bottom area of the cup shaped container. The molds are designed to improve the material distribution around the cup shaped container wall, the heel area and the bottom area over known cup shaped containers. In addition, when the cup shaped container is used in a coffee brewing machine, the design of the mold and the distribution of the material of the multi-layer sheet structure in the bottom area permit clean punctures by the coffee brewing machine in the bottom area of the cup shaped container.

Referring to the drawings, FIG. 1 is a cross sectional schematic illustration of an exemplary embodiment of a multi-layered sheet structure 10 that includes seven layers. Specifically, multi-layer sheet structure 10 includes an outer top layer 12 (also referred to herein as first layer 12) formed of a polypropylene composition, an inner top layer 14 (also referred to herein as second layer 14) formed of a polypropylene composition, a tie layer 16 (also referred to herein as third layer 16) formed of an adhesive material, a barrier layer 18 (also referred to herein as fourth layer 18), a tie layer 20 (also referred to herein as fifth layer 20) formed of an adhesive material, an inner bottom layer 22 (also referred to herein as sixth layer 22) formed of the polypropylene composition of inner top layer 14, and an outer bottom layer 24 (also referred to herein as seventh layer 24) formed of the polypropylene composition of outer top layer 12. The polypropylene composition of outer top layer 12 and the polypropylene composition of inner top layer 14 may be the same polypropylene composition, or different polypropylene compositions.

The polypropylene composition of first layer 12 includes a polypropylene. The polypropylene may be at least one of a polypropylene homopolymer, polypropylene copolymer, and blends with polypropylene and compatible polymers. The polypropylene composition may also include a color concentrate and an inorganic reinforcing agent. The color concentrate may include color pigments and/or dyes dispersed in solvents and/or a polymer compatible with polypropylene. Any suitable inorganic reinforcing agent may be used, for example, talc, mica, glass, silica, whiskers, wollastonite, carbon fiber, aramid fibers, and the like. The polypropylene composition of first layer 12 may include about 2 to about 6 percent by weight of the color concentrate, about 50 to about 70 percent by weight of polypropylene, and about 5 to about 60 percent by weight of the inorganic reinforcing agent, the weight percent based on the total weight of the polypropylene composition. Alternatively, the polypropylene of first layer 12 may include about 4 percent by weight of the color concentrate, about 61 percent by weight of polypropylene, and about 35 percent by weight of the inorganic reinforcing agent, the weight percent based on the total weight of the polypropylene composition of layer 12.

In another embodiment, the polypropylene composition of first layer 12 may also include a renewable plastics material or bioplastic, for example, a corn starch product. The corn starch product is a resin made from corn starch and referred to as Plastarch Material (PSM). Other bioplastics include, but not limited to, polylactic acid (PLA), modified PLA, polyhydroxyalkanoates (PHA), modified PHA, poly(hydroxybutyrate-co-valerate) (PHBV), poly(hydroxubutyrate-co-hexanoate) (PHBH), and blends of these bioplastics with other plastics, for example polypropylene, polyethylene, and the like. In this embodiment, the polypropylene composition of first layer 12 may include about 2 to about 6 percent by weight of the color concentrate, about 5 to about 65 percent by weight of polypropylene, about 5 to about 75 percent by weight of the renewable plastics material, and about 10 to about 40 percent by weight of the inorganic reinforcing agent, the weight percent based on the total weight of the polypropylene composition. Alternatively, the polypropylene composition of first layer 12 may include about 4 percent by weight of the color concentrate, about 46 percent by weight of polypropylene, about 20 percent by weight of the renewable plastics material, and about 30 percent by weight of the inorganic reinforcing agent, the weight percent based on the total weight of the polypropylene composition. In another embodiment, the polypropylene composition of first layer 12 may be 100 percent by weight of polypropylene, and in another embodiment first layer 12 may be 100 percent by weight of renewable plastics materials.

In a further embodiment, the multi-layer sheets described above that were not used and left over after a thermoforming process may be recycled and added to a virgin polypropylene composition. Multi-layer sheets and/or portions of the sheets that are left over after a thermoforming process are ground-up and added to a virgin polypropylene composition. The ground-up recycled material includes each of the materials used to form each layer of the multi-layer sheets. The polypropylene composition of first layer 12 may include up to about 50 percent of the recycled material. The use of recycled material facilitates producing economically viable products formed from multi-layered sheet structure 10.

The polypropylene composition of second layer 14 may be any of the embodiments of the polypropylene composition of first layer 12 described above. The polypropylene composition of first layer 12 and the polypropylene composition of second layer 14 may be the same polypropylene composition, or may be different polypropylene compositions.

The polypropylene composition of sixth layer 22 may be any of the embodiments of the polypropylene composition of first layer 12 described above, and the polypropylene composition of seventh layer 24 may be any of the embodiments of the polypropylene composition of first layer 12. The polypropylene composition of sixth layer 22 and the polypropylene composition of seventh layer 24 may be the same polypropylene composition, or may be different polypropylene compositions.

Any of the polypropylene compositions described above may be prepared by melt compounding the components with equipment known in the art. The equipment may include continuous and batch mixers, for example, Farrel Continuous Mixers available from Farrel Corporation, Ansonia, Conn., Banbury® mixers available from Farrel Corporation, single screw extruders, multiple screw extruders, and the like. In addition, compounding and melt mixing of the components in a continuous fashion, in-line with the production of extruded multi-layer sheet structure 10 may also be used.

Third layer 16 and fifth layer 20 are tie or adhesive layers formed of an adhesive material. The adhesive material is used to bond second layer 14 to fourth layer 18, and to bond sixth layer 22 to fourth layer 18. Suitable adhesive material that may be used include, but not limited to, a maleic anhydride grafted polypropylene adhesive, a functionalized polyethylene, a functionalized polypropylene, for example, a copolymer with polypropylene, a polyamide, blends of polyethylene and polypropylene containing active groups capable of reacting with the material of barrier layer 18.

Fourth layer 18 is a barrier layer and is formed by at least one of poly(ethylene vinyl alcohol) (EVOH), polyvinyl alcohol (PVOH), polyvinylidene chloride (PVDC), polyamide, acrylate copolymers, cyclic olefin copolymers, and the like. Fourth layer 18 may also include fillers, for example, active/passive scavengers, nanofillers including talc, glass, clay, silica, mica, and the like.

Multi-layer sheet structure 10 has a thickness of about 10 mil to about 135 mil. Alternatively, multi-layer sheet structure 10 has a thickness of about 10 mil to about 100 mil. Alternatively, multi-layer sheet structure 10 has a thickness of about 35 mil to about 60 mil. First layer 12 has a thickness of about 0.5 mil to about 15 mil, second layer 14 has a thickness of about 3.5 mil to about 77.5 mil, third layer 16 has a thickness of about 0.5 mil to about 5 mil, fourth layer 18 has a thickness of about 0.5 mil to about 5 mil, fifth layer 20 has a thickness of about 0.5 mil to about 5 mil, sixth layer 22 has a thickness of about 3.5 mil to about 77.5 mil, and seventh layer 24 has a thickness of about 0.5 mil to about 15 mil.

FIG. 2 is a cross sectional schematic illustration of an embodiment of a multi-layered sheet structure 30 that includes five layers. Specifically, multi-layer sheet structure 30 includes a top layer 32 (also referred to herein as first layer 32) formed of a polypropylene composition, a tie layer 34 (also referred to herein as second layer 34) formed of an adhesive material, a barrier layer 36 (also referred to herein as third layer 36), a tie layer 38 (also referred to herein as fourth layer 38) formed of an adhesive material, and a bottom layer 40 (also referred to herein as fifth layer 40) formed of a polypropylene composition.

The polypropylene composition of first layer 32 may be any of the embodiments of the polypropylene composition of first layer 12 described above and shown in FIG. 1, and the polypropylene composition of fifth layer 40 may be any of the embodiments of the polypropylene composition of first layer 12 described above and shown in FIG. 1. The polypropylene composition of first layer 32 and the polypropylene composition of fifth layer 40 may be the same polypropylene composition, or may be different polypropylene compositions.

Second layer 36 and fourth layer 38 are tie or adhesive layers formed of an adhesive material. The adhesive material is used to bond first layer 32 to third layer 36, and to bond fifth layer 40 to third layer 36. Suitable adhesive material that may be used include, but not limited to, a maleic anhydride grafted polypropylene adhesive, a functionalized polyethylene, a functionalized polypropylene, for example, a copolymer with polypropylene, polyamide, blends of polyethylene, and polypropylene containing active groups capable of reacting with the material of the third layer 36.

Third layer 36 is a barrier layer and is formed by at least one of poly(ethylene vinyl alcohol) (EVOH), polyvinyl alcohol (PVOH), polyvinylidene chloride (PVDC), polyamide, acrylate copolymers, cyclic olefin copolymers, and the like. Third layer 36 may also include fillers, for example, active/passive scavengers, nanofillers including talc, glass, clay, silica, mica, and the like.

FIG. 3 is a cross sectional schematic illustration of an embodiment of a multi-layered sheet structure 42 that includes three layers. Specifically, multi-layer sheet structure 42 includes a top layer 44 (also referred to herein as first layer 44) formed of a polypropylene composition, a barrier layer 46 (also referred to herein as second layer 46), and a bottom layer 48 (also referred to herein as third layer 48) formed of a polypropylene composition.

The polypropylene composition of first layer 44 may be any of the embodiments of the polypropylene composition of first layer 12 described above and shown in FIG. 1, and the polypropylene composition of third layer 48 may be any of the embodiments of the polypropylene composition of first layer 12 described above and shown in FIG. 1. The polypropylene composition of first layer 44 and the polypropylene composition of third layer 48 may be the same polypropylene composition, or may be different polypropylene compositions.

Second layer 46 is a barrier layer and is formed by at least one of poly(ethylene vinyl alcohol) (EVOH), polyvinyl alcohol (PVOH), polyvinylidene chloride (PVDC), polyamide, acrylate copolymers, cyclic olefin copolymers, and the like. Second layer 46 may also include fillers, for example, active/passive scavengers, nanofillers including talc, glass, clay, silica, mica, and the like.

FIG. 4 is a cross sectional schematic illustration of an embodiment of a multi-layered sheet structure 50 that includes two layers. Specifically, multi-layer sheet structure 40 includes a top layer 52 (also referred to herein as first layer 52) formed of a polypropylene composition, and a bottom layer 54 (also referred to herein as second layer 54) formed of a polypropylene composition.

The polypropylene composition of first layer 52 may be any of the embodiments of the polypropylene composition of first layer 12 described above and shown in FIG. 1, and the polypropylene composition of third layer 54 may be any of the embodiments of the polypropylene composition of first layer 12 described above and shown in FIG. 1. The polypropylene composition of first layer 52 and the polypropylene composition of second layer 52 may be the same polypropylene composition, or may be different polypropylene compositions.

Multi-layer sheet structure 10 may be fabricated by a co-extrusion process. Specifically, multi-layer structure 10 may be formed by co-extruding first layer 12, second layer 14, third layer 16, fourth layer 18, fifth layer 20, sixth layer 22 and seventh layer 24. A plurality of extruders are connected to a feed block that includes a die for extruding multiple layers at once. Three to nine extruders may be used, and the feed block connected to the extruders has a die for forming from 3 to 13 layers. At least one extruder may be used for each different material. In the exemplary embodiment, five extruders are used to feed the materials for each of the layers to the feed block to form the seven layers of multi-layer sheet structure 10. In alternative embodiments, four extruders or six extruders may be used to feed the materials for each of the layers to the feed block to form the seven layers of multi-layer sheet structure 10. Other co-extruding techniques can be used, for example, a multi-manifold die may be used instead of a feed block. In addition, groups of multiple layers may be co-extruded and then laminated together to form multi-layer sheet structure 10. For example first layer 12 and second layer 14 are co-extruded to form a first sheet, and third, fourth, and fifth layers 16, 18, and 20 are co-extruded separate from first and second layers 12 and 14 to form a second sheet. Also, sixth layer 22 and seventh layer are co-extruded separate from first, second, third, fourth, and fifth layers 12, 14, 16, 18, and 20 to form a third sheet. Then the three sheets are laminated to form multi-layer structure 10.

In the exemplary embodiment, multi-layer sheet structure 10 may be used for forming various articles, for example, cups and cup shaped containers. Specifically, cup shaped containers are formed using a plug assisted thermoforming process that utilizes cup shaped molds and plugs to assist sheet structure 10 into the mold and distribute the materials of multi-layer sheet structure around the mold to form a cup shaped container having a uniform wall, and uniform heel and the bottom area of the cup shaped container.

FIGS. 5-12 are schematic illustrations of various molds that may be used to mold articles, for example, cups and cup shaped containers from multi-layer sheet structure 10. Mold 70, shown in FIGS. 5 and 6, includes a forming insert 72 and a forming base 74. Forming insert 72 includes a mold cavity 76 and a base cavity 78 sized to receive forming base 74. Forming base 74 includes a top surface 80 that provides the shape of the bottom of a cup being molded. Mold 82, shown in FIGS. 7 and 8, includes a forming insert 84 and a forming base 86. Forming insert 84 includes a mold cavity 88 and a base cavity 90 sized to receive forming base 86. Forming base 86 includes a top surface 92 that provides the shape of the bottom of a cup being molded. Mold 94, shown in FIGS. 9 and 10, includes a forming insert 96 and a forming base 98. Forming insert 98 includes a mold cavity 100 and a base cavity 102 sized to receive forming base 98. Forming base 98 includes a top surface 104 that provides the shape of the bottom of a cup being molded. Mold 106, shown in FIGS. 11 and 12, includes a forming insert 108 and a forming base 110. Forming insert 108 includes a mold cavity 110 and a base cavity 112 sized to receive forming base 110. In addition, mold cavity 110 includes a plurality of flutes 114 in a wall 116 of mold cavity 110. Forming base 110 includes a top surface 118 that provides the shape of the bottom of a cup being molded. Molds 70, 82, 94, and 106 may be made from any suitable material, for example, steel, stainless steel, aluminum, and the like.

FIGS. 13-15 are bottom perspective schematic illustrations of plugs that may be used with the molds shown in FIGS. 5-12. Plug 120, shown in FIG. 13, includes a smooth bottom 122. Plug 124, shown in FIG. 14, includes raised and lower area of a bottom 126 to assist in forming the bottom of the cup being formed. Plug 128, shown in FIG. 15, includes raised and lower area of a bottom 130 to assist in forming the bottom of the cup being formed. Plugs 124 and 128 work synergistically with molds 70, 82, 94, and 106 to increase the cup heel thickness as compared to cups formed with plug 120. The increased heel thickness provides for increased strength of the cup heel as compared to cups formed with plug 120. Plugs 120, 124, and 128 may be made from any suitable material, for example, steel, stainless steel, aluminum, and the like. In addition, plugs 120, 124, and 128 may also include a plastic outer layer formed from, for example, an epoxy, a silicone, and the like.

FIGS. 16-23 include a side schematic illustration and a bottom perspective schematic illustration of various cup designs formed from multi-layer 10. Each cup includes a cup wall 121, a heel 123, and a bottom area 125. Cup 131, shown in FIGS. 16 and 17, has an increased stack ledge depth 132 and a reduced heel corner radius 134 compared to known cups. Cup 131 may be formed in mold 70 shown in FIGS. 5 and 6. Cup 140, shown in FIGS. 18 and 19, has an increased stack ledge depth 142 and a reduced heel corner radius 144 compared to known cups. In addition, cup 140 includes an added center radius 146 for strength. Cup 140 may be formed in mold 82 shown in FIGS. 7 and 8. Cup 150, shown in FIGS. 20 and 21, has an increased stack ledge depth 152 and a reduced heel corner radius 154 compared to known cups. In addition, cup 150 includes two added center radius for strength 156. Cup 150 may be formed in mold 94 shown in FIGS. 9 and 10. Cup 160, shown in FIGS. 22 and 23 has an increased stack ledge depth 162 and a reduced corner radius 164 compared to known cups. In addition, cup 160 includes added flutes 166 to a bottom portion 168 of cup wall 120 for strength. Cup 160 may be formed in mold 106 shown in FIGS. 11 and 12.

This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims. 

1. A multi-layer sheet structure comprising: a barrier layer having a first side and a second side; at least one thermoplastic layer on said first side of said barrier layer; and at least one thermoplastic layer on said second side of said barrier layer.
 2. The multi-layer sheet structure in accordance with claim 1 wherein said at least one thermoplastic layer on said first side of said barrier layer comprises a first layer comprising a first polypropylene composition, and said at least one thermoplastic layer on said second side of said barrier layer comprises a second layer comprising a second polypropylene composition.
 3. The multi-layer sheet structure in accordance with claim 2 further comprising a first adhesive layer between said first side of said barrier layer and said first layer, and a second adhesive layer between said second side of said barrier layer and said second layer.
 4. The multi-layer sheet structure in accordance with claim 3 further comprising a third layer comprising a third polypropylene composition on said first layer.
 5. The multi-layer sheet structure in accordance with claim 4 further comprising a fourth layer comprising a fourth polypropylene composition on said second layer.
 6. The multi-layer sheet structure in accordance with claim 5 further comprising a fifth layer comprising a fifth polypropylene composition on said third layer.
 7. The multi-layer sheet structure in accordance with claim 6 further comprising a sixth layer comprising a sixth polypropylene composition on said fourth layer.
 8. The multi-layer sheet structure in accordance with claim 2 wherein said first and second polypropylene compositions comprise a polypropylene and optionally at least one of a color concentrate, an inorganic reinforcing agent, and a bioplastic material, said first polypropylene composition is the same as said second polypropylene composition, or different from each other.
 9. The multi-layer sheet structure in accordance with claim 2 wherein said first and second polypropylene compositions further comprise up to 50% of recycled material comprising unused reground multi-layer sheet structures.
 10. The multi-layer sheet structure in accordance with claim 8 wherein said bioplastic material comprises at least one of a resin made from corn starch, polylactic acid materials (PLA), polyhydroxyalkanoates materials (PHA), poly(hydroxybutyrate-co-valerate) (PHBV), poly(hydroxubutyrate-co-hexanoate) (PHBH), and blends of said bioplastic materials at least one of polyethylene and polypropylene.
 11. The multi-layer sheet structure in accordance with claim 1 wherein said barrier layer comprises at least one of poly(ethylene vinyl alcohol) (EVOH), polyvinyl alcohol (PVOH), polyvinylidene chloride (PVDC), polyamide, acrylate copolymers, and cyclic olefin copolymers.
 12. The multi-layer sheet structure in accordance with claim 11 wherein said barrier layer further comprises least one of active scavengers, passive scavengers, talc, glass, clay, silica, and mica.
 13. The multi-layer sheet structure in accordance with claim 1 wherein said multi-layer sheet structure does not include said barrier layer.
 14. A multi-layer sheet structure comprising: a barrier layer having a first side and a second side; a first adhesive layer on said first side of said barrier layer; a second adhesive layer on said second side of said barrier layer; a first layer on said first adhesive layer, said first layer comprising a first polypropylene composition; and a second layer on said second adhesive layer, said second layer comprising a second polypropylene composition.
 15. The multi-layer sheet structure in accordance with claim 14 wherein said first layer comprises a plurality of first thermoplastic layers, each of said plurality of first thermoplastic layers comprising a polypropylene composition.
 16. The multi-layer sheet structure in accordance with claim 15 wherein said second layer comprises a plurality of second thermoplastic layers, each of said plurality of second thermoplastic layers comprising a polypropylene composition.
 17. The multi-layer sheet structure in accordance with claim 14 wherein said first and second polypropylene compositions comprise a polypropylene and optionally at least one of a color concentrate, an inorganic reinforcing agent, and a bioplastic material, said first polypropylene composition is the same as said second polypropylene composition, or different from each other.
 18. The multi-layer sheet structure in accordance with claim 17 wherein said first and second polypropylene compositions further comprise up to 50% of recycled material comprising unused reground multi-layer sheet structures.
 19. The multi-layer sheet structure in accordance with claim 17 wherein said bioplastic material comprises at least one of polylactic acid materials (PLA), polyhydroxyalkanoates materials (PHA), poly(hydroxybutyrate-co-valerate) (PHBV), poly(hydroxubutyrate-co-hexanoate) (PHBH), a resin made from corn starch, and blends of the bioplastic materials with at least one of polyethylene and polypropylene.
 20. The multi-layer sheet structure in accordance with claim 14 wherein said barrier layer comprises at least one of poly(ethylene vinyl alcohol) (EVOH), polyvinyl alcohol (PVOH), polyvinylidene chloride (PVDC), polyamide, acrylate copolymers, and cyclic olefin copolymers.
 21. A method of making a multi-layer sheet structure, said method comprising: connecting a plurality of extruders to a die configured to extrude a plurality of layers; feeding a plurality of thermoplastic materials to the plurality of extruders; and co-extruding a plurality of layers from the plurality of thermoplastic materials to form the multi-layer sheet structure, the plurality of layers comprise: a barrier layer having a first side and a second side; at least one thermoplastic layer on the first side of the barrier layer; and at least one thermoplastic layer on the second side of the barrier layer.
 22. The method in accordance with claim 21 wherein connecting a plurality of extruders to a die comprises connecting the plurality of extruders to a feed block having a die configured to extrude a plurality of layers.
 23. The method in accordance with claim 21 wherein connecting a plurality of extruders to a die comprises connecting the plurality of extruders to a multi-manifold die configured to extrude a plurality of layers.
 24. The method in accordance with claim 21 wherein co-extruding a plurality of layers comprise co-extruding: a barrier layer having a first side and a second side; at least one thermoplastic layer covering the first side of the barrier layer; and at least one thermoplastic layer covering the second side of the barrier layer.
 25. The method in accordance with claim 24 wherein co-extruding comprises co-extruding: a barrier layer; a first layer onto the first side of the first side of the barrier layer, the first layer comprising a first polypropylene composition; and a second layer onto the second side of the barrier layer, the second layer comprising a second polypropylene composition.
 26. The method in accordance with claim 25 wherein co-extruding further comprises co-extruding: a first adhesive layer between the first side of the barrier layer and the first layer; and a second adhesive layer between the second side of the barrier layer and the second layer.
 27. The method in accordance with claim 26 wherein co-extruding further comprises co-extruding: at least one layer onto the first layer, the at least one layer comprising a third polypropylene composition.
 28. The method in accordance with claim 27 wherein co-extruding further comprises co-extruding: at least one layer onto the second layer, the at least one layer comprising a fourth polypropylene composition.
 29. The method in accordance with claim 27 wherein co-extruding further comprises co-extruding: co-extruding a first group of layers; co-extruding a second group of layer; and laminating the first group of layers to the second group of layers.
 30. The method in accordance with claim 25 wherein the first and second polypropylene compositions comprise a polypropylene and optionally at least one of a color concentrate, an inorganic reinforcing agent, and a bioplastic material, the first polypropylene composition is the same as the second polypropylene composition, or different from the second polypropylene.
 31. The method accordance with claim 25 wherein the first and second polypropylene compositions further comprise up to 50% of recycled material comprising unused reground multi-layer sheet structures.
 32. The method in accordance with claim 30 wherein the bioplastic material comprises at least one of polylactic acid materials (PLA), polyhydroxyalkanoates materials (PHA), poly(hydroxybutyrate-co-valerate) (PHBV), poly(hydroxubutyrate-co-hexanoate) (PHBH), a resin made from corn starch, and blends of the bioplastic materials with at least one of polyethylene and polypropylene.
 33. The method in accordance with claim 21 wherein the barrier layer comprises at least one of poly(ethylene vinyl alcohol) (EVOH), polyvinyl alcohol (PVOH), polyvinylidene chloride (PVDC), polyamide, acrylate copolymers, and cyclic olefin copolymers.
 34. A multi-layer sheet structure comprising: a first layer; and a second layer; said first layer comprise a first polypropylene composition and said second layer comprise a second polypropylene composition.
 35. The multi-layer sheet structure in accordance with claim 34 further comprising a barrier layer positioned between said first layer and said second layer.
 36. The multi-layer sheet structure in accordance with claim 35 further comprising: a first adhesive layer positioned between said barrier layer and said first layer; and a second adhesive layer positioned between said barrier layer and said second layer.
 37. The multi-layer sheet structure in accordance with claim 36 further comprising at least one cap layer positioned on said first layer, said at least one cap layer comprising a third polypropylene composition.
 38. The multi-layer sheet structure in accordance with claim 37 further comprising at least one cap layer positioned on said second layer, said at least one cap layer comprising a fourth polypropylene composition.
 39. The multi-layer sheet structure in accordance with claim 34 wherein said first and second polypropylene compositions comprise a polypropylene and optionally at least one of a color concentrate, an inorganic reinforcing agent, and a bioplastic material, said first polypropylene composition is the same as said second polypropylene composition, or different from said second polypropylene composition.
 40. The multi-layer sheet structure in accordance with claim 34 wherein said first and second polypropylene compositions further comprise up to 50% of recycled material comprising unused reground multi-layer sheet structures.
 41. The multi-layer sheet structure in accordance with claim 39 wherein said bioplastic material comprises at least one of a resin made from corn starch, polylactic acid materials (PLA), polyhydroxyalkanoates materials (PHA), poly(hydroxybutyrate-co-valerate) (PHBV), poly(hydroxubutyrate-co-hexanoate) (PHBH), and blends of said bioplastic materials at least one of polyethylene and polypropylene.
 42. The multi-layer sheet structure in accordance with claim 35 wherein said barrier layer comprises at least one of poly(ethylene vinyl alcohol) (EVOH), polyvinyl alcohol (PVOH), polyvinylidene chloride (PVDC), polyamide, acrylate copolymers, and cyclic olefin copolymers.
 43. The multi-layer sheet structure in accordance with claim 42 wherein said barrier layer further comprises least one of active scavengers, passive scavengers, talc, glass, clay, silica, and mica. 